There is an understandable temptation to attempt to grow dahlias in pots for a myriad of reasons. We all love dahlias. As well, many dahlia lovers living in urban areas may not have a backyard in which to create a garden. With this in mind, we decided that we would be remiss if we did not highlight some of the inherent unforeseen frustrations associated with growing dahlias in pots. To be clear, dahlias may grow in pots. Still, many may not come up in a potted setting, or may struggle to thrive. This information is not intended to discourage. Instead, it is intended to provide dahlia lovers with tips to support their success when planting dahlias in a pot. As always, we share with you the dream of gorgeous blooms in any environment.
Know Before You Grow
If a grower decides to plant dahlias in a pot, we recommend selecting dwarf varieties, or varieties bred specifically for growth in a contained area (typically small ones). (Please note: Bear Creek Farm does not sell dahlias meant to be pot varieties. Our tubers may do well, but they are outside our guarantee.)
Why Don’t Dahlias Tend to Thrive in Pots?
Dahlias have a reputation for being finicky. This characterization is, to our way of thinking, not quite fair. They need what they need – and what they deliver is splendid. Read on to discover why dahlias often struggle in pots – and how to better your chances of producing a robust bloom, nevertheless.
- Dahlias need a comparatively large amount of space in which to grow. Dahlias have an extensive root system (which grows sideways). When these roots run out of space, their overall health is affected, and they may fail to thrive.
- Soil. Dahlias require well-drained soil. This is something nature tends to facilitate more easily than can be created in potted plants – as the latter must grow in a fundamentally more static environment. Dahlias in pots lack the organic fluidity of optimal drainage found as naturally occurring in outside garden beds. The soil required for healthy dahlia growth needs to be nutrient-rich. Often, when soil is packed in a pot, it becomes compact and the hungry-root system of a dahlia depletes the nutrients. This is why the grower may be disappointed by a “less- than” or anemic bloom atop a stem. For this reason, we recommend that growers pay close attention to soil maintenance.
- Watering & Drainage Problems. When growers planting dahlias in a pot do so, getting the correct calibration between over-watering and under-water may prove to be difficult. If one overwaters the dahlia, it can cause the source tuber to rot due to sitting water or gradual over saturation - stifling its ability to produce. On the other hand, insufficient watering can stress the nascent bloom as a thirsty dahlia requires adequate hydration. This in-and-out water/drainage rhythm is difficult for the human hand to replicate without the benefit of the spaciousness of earth and nature, even with pebbles and drainage holes within pots.
- Changes in Temperature. Potted dahlias are more prone to suffer from variable or unpredictable changes in temperature, than those planted in the ground. Sudden or extreme shifts between unseasonably mild or unexpectedly cold temperatures stress potted dahlias more than they do their in-ground counterparts. (This may adversely impact the hoped-for healthy bloom.)
Pro Tips for Dahlias in a Pot
At Bear Creek Farm, where we nurture beauty from the ground up, we always encourage our friends to take chances. In so doing, we also like to empower gardeners with information to enhance the chances of their success. Sometimes, beginning something with “eyes wide open,” enables a grower to cope with risk – while integrating necessary findings. In addition, understanding apparent “failure” (a word we dislike) as common experience can spur a grower on, informing changes in future plans - rather than accepting defeat as an inevitable outcome. With this in mind:
Should one wish to grow dahlias in a pot:
- Make sure to choose a large pot. In selecting a large pot (at least 5 gallons), a gardener is providing maximum opportunity for healthy root systems to develop, thereby supporting overall stem and bloom health.
- Make sure to use high quality soil. Again, remember that dahlias are a nutrient hungry blossom. (How else could they possibly produce the worlds of color, and complex petal formation for which they are known – here, we bow down to the miracle of soil.)
- Do not be hoodwinked by pots that are more decorative than they are functional. We get it, we do. When planting a real beauty of a flower, one wishes to enhance the hoped for end goal. As such, a gorgeous, lacquered pot sitting in a nursery may be tempting. And one may well find just the thing. We only caution that buyers select a pot that will provide adequate drainage rather than a specific aesthetic. In placing the pot, wherever the locale, be mindful of drainage – run-off water needs a place to go. If a pot is placed outside (on a front stoop, a window box, or a fire escape) be especially aware of variable temperatures and be prepared to bring dahlias pots in as necessary.
- Adapt a regime of regular feeding. Having started with nutrient-rich soil, remember that dahlias are hungry and need to be fed. Consider augmenting your nutrient-rich soil with balanced, organic fertilizer as this can help potted dahlias achieve their greatest bloom.
Now that you've finished reading this article, you should check out our tulip planting primer, dahlia growing guide, and cutting guide for dahlias. And if you're shopping for dahlia tubers, make sure to check out our giant dahlia tubers (10"+ blooms), micro dahlia tubers (under 2" blooms), dark pink dahlia tubers, dark red dahlia tubers, and bicolor dahlia tubers.